1. Field of the Invention
The present invention relates to a hardware control technique for processing a raster image formed by an image compression apparatus.
2. Description of the Related Art
Recently, an MFP (Multi-Function Peripheral) which forms an image by an electrophotographic method performs various kinds of handling for image data. For example, the following methods are conceivable as processing for raster image data after rasterizing PDL (Page Description Language) data.
For example, as the first method, raster image data directly undergoes image processing such as color processing, and is output to a printer engine. As the second method, raster image data read out from a memory is developed into a rectangular image, and the rectangular image is encoded and then transferred to another device. As the third method, after raster image data is developed into a rectangular image, the rectangular image undergoes rotation processing without changing the unit of the rectangular image. To perform these processes, the MFP includes a dedicated processor module capable of mutually converting raster image data and tile image data (Japanese Patent Laid-Open No. 2004-157609). The main CPU of the MFP sets an operation mode in a mode information storage unit such as a register in accordance with the sequence of image data processes, implementing various image processes and image data processing sequences.
In Japanese Patent Laid-Open No. 2004-157609, after rendered raster image data is stored once in a DRAM, the image data needs to be divided into rectangles. As the image quality improves, the data transfer amount between the DRAM and the image processing circuit increases, and the processing performance of the MFP may not be achieved. In both the scan line method and painter method generally known as PDL data rendering methods, it is difficult to divide raster image data into rectangles unless at least part of the rendered raster image data is stored in the memory. For example, a large-capacity line buffer is required to divide rendered image data into rectangles without the intervention of the DRAM, failing in rendering processing independent of the printer resolution.